The invention relates to device for mowing plants that can be used, for example, in agriculture for mowing blade fodder and cereals.
For mowing fodder plants and cereals on agriculturally used areas, finger bar mowing devices and double blade mowing devices are used whose blades carry out an oscillating movement. Finger bar mowing devices have blade bars that move on a sine curve and have blades that force the material to be mowed against stationary mowing fingers provided with a counter edge so as to cut according to the principle of a scissor cut.
In the case of double blade mowing devices, a second blade bar moving in opposite direction provides the required counter edge.
Because of the sine-shaped movements, these mowing devices do not operate at a constant cutting speed but within a speed range of zero up to a limited maximum speed. The latter is limited to a few meters per second as a result of the occurring mass forces.
In principle, it is to be assumed that the oscillating mowing devices enable only a limited traveling speed and efficiency per unit area. In particular, finger bar mowing devices have the tendency to clog in the case of lush and herbaceous plants as well as to deliver unsatisfactory cutting qualities in the case of blade wear.
A second group of mowing devices are the rotary mowers which are configured either as drum mowing devices or as disk mowing devices. They have developed into the dominant technology in mowing under the conditions of modern European agricultural operations. In the case of drum mowing devices, the drive elements are arranged in a portal arrangement above the cutting plane while in the case of disk mowing devices the drive elements are arranged underneath the cutting plane. The drum mowing devices as well as the disk mowing devices operate according to the free cut principle, i.e., without a counter blade. In order to ensure free cutting as a result of inertia of the plants to be cut, these mowing devices generally are operated at a cutting speed above 70 m/s. Accordingly, rotary mowers require a very high drive power. Because of the resulting kinetic energy of the rotating parts, particularly the mowing blades and solid bodies (for example, rocks) accelerated by them, represent a significant risk of injury. The mowing blades have a material thickness of 3–4 mm. As a result of wear that occurs because of the cutting principle, the cutting edges will become round and therefore carry out more of a tearing than a cutting action. This leads to microscopically torn cutting surfaces on the individual stems and accordingly to growth depression in the following growing phase. Because of the translatory traveling movement and the circular blade movement, the rotor mowers carry out a cut only in the leading area so that therefore multiple cuts can be performed accidentally so that an increased wear and power output can not be excluded. As a result of their configuration, the disk mowing devices can be combined easily with processing tools in the form of crushing rollers or beater rotors for accelerating drying.
Moreover, drum-shaped and disk-shaped mowing devices are known that are used for cultivated specialty plants or as mowing attachments on crop choppers.
In the field of gardening, for cutting plants at locations that are difficult to access mowing devices are used that are comprised of a rotating plastic thread that also operates according to the free cut principle. In forestry, and in landscape cultivation, free cutters with working elements that are similar to a saw blade are used in order to cut shrubs and plants that have a strong stalk.
The patent literature discloses furthermore solutions where blade plants are cut with a circulating cutting tool in the form of a chain provided with cutting teeth (for example, U.S. Pat. No. 4,070,810; WO 96/32832). In place of the chain, a circulating endless V-belt is used as a support element in another document (DE 2707030).
Another known solution, in particular for mowing a lawn with a minimal working width, is realized by using cutting belts. For ensuring the cutting process, they are either maintained in a sharp state like a scythe (DE 4231665) or they are provided with cutting teeth (for example, U.S. Pat. No. 3,425,196; DE 3427900). These belts are either manufactured exclusively of steel or employ a different belt-shaped support material, for example, a fabric, plastic materials, or composite materials. For improving the cutting process, often finger-shaped counter holders are proposed that are designed to counteract yielding of the plants to be cut.
For an improved adaptation to the ground in the belt mowing machines, either guide rails with hinges (DE 2929184) or mowing systems that are assembled of individual mowing machines (U.S. Pat. No. 3,656,285) are proposed.
It is an object of the invention to provide a device with which the cutting process for a great working width can be realized with a high energy efficiency and which device requires only minimal manufacturing costs. Damage and wear occurring on the cutting belts are to be minimized. At the same time, it is to be ensured that, with only minimal retooling measures, the mowing machine, depending on the application, can operate according to the principle of a free cut as well as in interaction with counter holders and that, as needed, a processing effect can be obtained by providing corresponding auxiliary devices.